The present invention relates to separately heating and cooling multiple containers or multi-chamber containers. In particular, the present invention relates to heating a sample and/or reagent container in the incubator of a clinical analyzer.
Known analyzers may include an incubator for heating a container, such as a cuvette, having sample and reagent(s) added thereto to a selected temperature, e.g., 37° C., to allow for reaction between the sample and reagent. In many analyzers, multiple cuvettes or multi-chamber cuvettes are used simultaneously to increase sample throughput in the analyzer. An example of a known incubator 10 is shown in FIG. 1. In the incubator shown in FIG. 1, multi-cell cuvettes, such as shown in FIG. 2, are inserted into rows 11. The rows are separated by wall sections 13 that extend from base 12 and are used to transfer heat from the base 12 to the cuvette 20.
Multiple cuvettes or multi-chamber cuvettes (hereinafter collectively referred to as multi-chamber cuvettes), such as those described for example in U.S. Patent Application Publication No. 2003/0003591 A1, Des. 290,170 and U.S. Pat. No. 4,639,135 and shown in FIG. 2, or microtiter plate assay based analyzers do not always fill all of the cuvettes/cells in the same manner. When automated analyzers are used in a random access mode, fluid can be added to cuvette cells which adjoin cells that may be either empty or full. The addition of fluid to these cells can have a large impact on the thermal kinetics of the adjoining cells. For example, in some automated analyzers, reagent is stored on the analyzer at about 8° C. When the reagent is added to the cuvette cell it significantly cools the cuvette cell as well as the surrounding cells.
It is important to prevent or minimize heat transfer between cells because cooling of adjacent cells can negatively affect the reaction between reagent(s) and sample in these cells or have other negative effects, thus affecting the precision of the assays. To reduce or minimize heat transfer, cuvettes have been designed to reduce thermal transfer across the cells. FIG. 2 shows a known multi-cell cuvette 3 having gaps 1 between the individual cells 2 to control the transfer of heat between the cells. FIG. 2 also shows disposable aspirating/dispensing tip 3.
While improved cuvette designs such as shown above have helped with the problem of heat transfer, heat energy can also transfer through the incubator metal parts. This enables the temperature of the fluid in one cell to influence the temperature in the next even if the cuvette design itself completely blocks heat transfer between cells.
In addition to the heat transfer from the addition of cold or hot fluids, there is also detrimental heat transfer that occurs when loading new cuvettes into the incubator. These cuvettes typically enter the incubator at room temperature. The current method for bringing the cuvettes up to incubator temperature is to place the new cuvette into a warm up slot. There is, however, still a temperature influence on the full incubator block when these cold cuvette strips are loaded, because the warm-up slot is generally not thermally isolated from the rest of the cuvette. Another way to reduce the impact of this issue is to pre-heat the cuvettes, however, this adds additional costs to the incubator.
A similar problem occurs in microtiter plates, both when the plate is not fully used, and also at the edges of the microtiter plate. Those cells that are at the boundary, either because there is no fluid in adjacent cells or because they are on the edge, will in a normal incubator design have a faster thermal rise than in the other cells. This can influence the precision of the assays.
In the known microtiter plate art separate heaters and controllers can be used to control each of the cell locations. An example is described in DE 3941168A1. These types of heaters are typically used for polymerase chain reaction (“PCR”) processing in microtiter plates. Other types of microtiter plates have an air gap between the cells and the heater plate, such as those used in the Ortho Summit Processor sold by Ortho-Clinical Diagnostics, Inc. Microtiter plate heaters of this type have slower thermal rise times and are thus not as prone to inconsistent heating. That is, the air gap reduces or eliminates thermal cross talk across the heater (although edge effects can still occur). However, the disadvantages of these designs are slower thermal rise times, which results in slow heating. Faster and more controlled thermal rise times make it necessary to implement designs that have more intimate contact with the microtiter plate and therefore are more prone to thermal cross talk.
For the foregoing reasons, there is a need for a device, such as an incubator that has a simplified structure, provides for quicker heating/cooling times and provides increased thermal isolation between cells containing the liquid being heater or cooled.